Method of forming lumpy deposits by spraying



May 4, 1954 v. H. BoDLE ETAL METHOD oF FORMING vLUMPY nEPosI'rs BYSPRAYING Filed March 17, 1950 /ffff/ #zw 5e May 4, 1954 v. H. BoDLE ETAL METHOD 0F FORMING LUMPY DEPosITs BY SPRAYING Filed March 17, 1950 2Sheets-Sheet 2 Patented May 4, 1954 UNITED STATES TENT OFFICE METHOD OFFORMING LUMPY DEPOSITS BY SPEAYING Application March 1'7, 1950, SerialNo. 150,184

4 Claims.

Our invention relates to the production of suriacings or layers ofmaterial by spraying a coagulable dispersion of rubber or thevlilee, andhas reference more particularly to such suriacings or layers, and themethod of and equipment for producing same, wherein the spray particlesare deposited in a manner and in such volume to accumulate to asubstantial depth and in individualized piles or lumps forming acontiguity of pronounced protuberances or lumps, this application beinga continuation in part oi our co-pending application Serial No. 550,964(now Patent 2,501,839) led August 24, 1944.

The principal objects of our invention are to provide a new and improvedmaterial from a spray of coagulable dispersion of rubber or the like,and an improved method of spraying and equipment by which the materialmay be readily and economically produced; to permit the production oisuriacings and layers, from such dispersions, of substantial depth orthickness Withut repeated spray applications and intermediate drying orcoagulation periods; to effect accumulation or" the spray particles inclusters or piles ci such size and individuality to form a continuity ofpronounced protuberances or lumps; to permit the material to be madeoptionally as a surfacing attached to a backing or as an independentlayer; to agglomerate the spray particles of each protuberance or lumpin an integrated tough mass capable of withstanding hard wear; and topermit rapid and continuous production of the material, these and otherobjects being accomplished as pointed out hereinafter and as shown inthe accompanying drawings, in which:

Fig. l is a top view showing somewhat diagrammatically a prefered formand arrangement of equipment for making sprayed material in accordanceour invention;

2 is a view, partly in section, taken substantially on the line 2--2 ofFig. 1;

E is a View greatly enlarged, on the line l-t oi Fig. 2 showing thepaired latex and coagulant spray guns (one in section) which contributeprincipally to the building up of the pile or lump formations;

Fig. i is a side View showing diagrammatically another arrangement ofequipment for producing the material of this invention;

Fig. 5 is a top view of the equipment illustrated in Fig. fi;

Fig. 6 is a top view of a section of sprayed surface in an initial stageof the spraying operation;

Fig. '.7 is a View similar to Fig. 6 but showing the sprayed surface ina later stage of the spraying operation;

Fig. 8 is a fragmentary sectional view showing the manner in which thespray particles accumulate in piles or lumps; and

Fig. 9 is a similar View showing an increase in the build up of thepiles or lumps of Fig. 8.

I-leretoiore in producing materials from a sprayed dispersion of rubberor the like, it has been the practice either to deposit the sprayparticles in successive thin continuous films which collectively producea solid deposit of the desired thickness, or to spray the dispersion ininsucient quantity to produce a continuous nlm, so that the particlesare sparsely applied and produce a rough superficial surface the textureof which depends upon thc spray particle size.

Generally the spray particles are deposited in uncoagulated state anddried or coagulated on the surface after deposit, although it has beensuggested that they may be coagulated immediately before deposit,

Zimmerli and Semon Patent 1,841,076 is illustrative of the solid depositpractice and in their procedure the deposit is produced by successiveapplications of the dispersion spray which is exposed to a coagulantvapor or mist so that the particles coagulate after they reach thesurface. Similarly in Galligan Patent 2,191,910 a continuous thin rubbernlm or solid rubber base layer is produced in a pattern form byalternate sprays of dispersion and coagulant so that relatively slowcoagulation of the dispersion particles cccurs on the sprayed surface.

Mayne Patent 2,056,406 is illustrative oi the roughened surfacingapplications, the dispersion spray being deposited in insucient quantityto produce a continuous nlm and the particles being either deposited onpreviously applied coagulant or sprayed through a mist of coagulant sothat they coagulate immediately upon deposit.

Similarly in Hansen Patent 2,120,406, Diller Patent 2,306,937 andSchwartz Patent 2,184,153 the dispersion particles are applied so as toproduce a non-continuous nlm and the particles are coagulated afterdeposit. In the above mentioned Galligan patent, in which a roughsurfacing is produced on his solid rubber base, by spraying adiscontinuous lm of dispersion particles thereon, it is suggested thatthese particles constituting the discontinuous nlm may be coagulatedeither before or after deposit.

We have found that by simultaneously or conjointly depositing acombination or mixture oi coagulated and uncoagulated spray particles agreatly1 increased spray volume may be employed and an integrateddeposit of substantially any desired depth or thickness may be producedprogressively without intermediate drying or coagulation periods.

We have found further that by properly proportioning the 4coagulated anduncoagulated spray particles,the deposit may be built up to the desireddepth in suiciently separated or individualized piles to provide asurfacing or layer in the form of a contiguity of pronouncedprotuberances or lumps.

These protuberances or lumps may be more or less individualized, as forlexample either substantially completely individualized or interconnecteda substantial distance upwardly from the bottom, both as shown in ouraforesaid application Serial No. 550,964 and they may be of elongatedringer-like form as illustrated particularly in our said application orof more squatty and less finger-like form, as shown hereinydepending onthe volume of the dispersion sprayed on a -given area and-the proportionemployed of coagulated to-uncoagulated particles.

Moreover the places of build up in the individualized piles may bepredetermined by Spraying on a surface, such as illustrated in ouraforesaid application, having embossments upon which'the build up issubstantially localized, or

' rthe build up may be caused to occur at random locations, ashereinafter more fully explained,

by appropriate spray technique, on a smooth surface.

Furthermore, with our method, the texture of the sprayformed-projections or lumps may be varied and the particles of whichthey are formed may be accumulated and integrated in relatively solidmasses of such toughness that the material is capable ofwithstandinghard wear and is suitable for such purpose as carpeting, automobileloormats and even shoe soles.

Fine particles alone may be employed to build up the more or lessindividualized finger-like piles or lumps of our invention, but it isdesirable to employ a spray wherein a considerable -proportion of thedeposited particles are of larger size.

This is advantageous, not only because the larger size particles buildup more rapidly in the ringer or lump-like piles and tend to corn- `pactthe deposit, but it is particularly important in depositing on a planesurface as it provides an initial Adeposit of separate masses of suchsize that subsequently deposited particles tend to accumulate and pileup thereon and thus the ini tiation of the separate piles isfacilitated.

` Thistendency of the particles to accumulate Aand build up inindividualized piles is believed f to be due to electrostatic action,the spray par- .aresprayed in an electrostatic eld as hereinafterexplained, from which it is `assumed that the piling up, in any event,is due to electrostatic action and that the sprayed particles normallytend to accumulate some charge, perhaps by friction in the air.

'4 In practicing our invention we have found it advantageous to employequipment, such as shown somewhat diagrammatically in Figs. 1 and 2,wherein a. pair of spray guns are arranged to produce a combined rubberdispersion and coagulant spray which deposits on the surface on I.whichthe sprayed surfacing or layer is to be produced,. and wherein anothersingle spray gun is arranged to spray rubber dispersion only on thedeposited combined dispersion and coagulant spray from the V,pair ofspray guns.

In said'V Figs. l and 2, the reference numeral I0 indicates a` conveyorbelt on the horizontal upper length of which the spray is deposited orupon which a sheet of material or separate sec- .2 tions of sheetmaterial are advanced through the spraying zone. This conveyor belt isof a width corresponding to the desired width of material to be madethereon, for example 60 inches in the present set up, and is trainedaround rollers or drums II' and I2', to one of which power is appliedfrom a suitable source to operate the belt in the direction indicated bythe arrows at a speed generally between three and four feet per minute,and preferably closer to three feet per minute.

A metal plate I3 underlies and supports the upper length of the belt IDthroughout the area of the spray zoneand is grounded as indicated at I4for a purpose hereinafter explained.

Above the belt IB at the forward end of the metal plate I4 is located apair of spray guns (see Fig. 3), one of which, indicated at I5 suppliesa spray of theV rubber dispersion and the other of which, indicated atI6 supplies a spray of liquid coagulant.

Each of the nozzles I5 and I6 has a short laterally extending mountingarm I1 pivote@ by means of a bolt I8 to a connector block IS which ishorizontally pivoted to the lowerend of a hanger 20 by means of a bolt2! which extends at right angles to the bolt I.

The hanger 20 depends from a wheeled carriage or trolley `I2I whichoperates on an over head track 22 which .extends transversely of thebelt I0 from side to side.

Thus the spray guns I5 and I6 are movable conjointly to and fro acrossthe belt width and are conjointly adjustable on the bolt connection 2Ito any desired angle relatively to the belt iii and each nozzle isindividually adjustable on the bolt 8 to any desired angle relatively tothe belt length and to one another.

These spray guns I5 and I6 are located approximately 36 inches above theupper length of the belt Ill and are conjointly tippe-d downwardly atanangle of approximately 50 to the surface of the beltv and are adjustedangularly with respect to one another and to the belt length so that thesprays therefrom meet a short distance from the guns andV produce acombined dispersion and coagulant spray in a plane lengthwise of thebelt. Because the volume and force of the dispersion spray issubstantially greater than that of the coagulant spray, the direction ofthe combined spray is determined principally by the dispersion spray andaccordingly the coagulant gun I6 is at a m'uch greater sidewise angle tothe direction of movement of the belt than the dispersion gun I5.

Any conventional spray guns of appropriate volume and. control of thespray Vconstituents may be employed', those shown. herein, like thoseof4 our aforesaid.A application Serial No. 550,964, being made byPaasche Spray Equipment Company of Chicago, Illinois, although we haveused and found spray guns made bylBinks Manuiacturing Company ofC-hioago, Illinois, produce equally satisfactory results. Spray gunshaving valves which permit adjustment of the size of the spray orificeand the air volume have been found advantageous, as they permitregulation of the quantity and character of the spray.

The guns I5 and I6 are alike, except as to spray capacity and eachcomprises a body having two ports 23 and 24 leading therethrough, theport 23 leading to the chamber 25 of a cap 26 which is threaded onto thebody and the port 2li leading to a nozzle 21 which is also threaded ontothe `body and projects centrally through the chamber 25 of the cap 26.

The nozzle body has a flexible hose 28 connected thereto at the outerend of the port 23 and leading from a source of compressed air to supplyair under pressure to the chamber 25 and the latter has an outlet 29therefrom which surrounds the tip of the nozzle 21 so that compressedair discharges therefrom in a nozzle tip encircling stream.

Each nozzle body also has another flexible hose connected thereto at theouter end of the port 2d to supply the liquid which is to be sprayedthrough the nozzle 21, such exible hose for the spray gun I5 beingindicated at 30 and connected to a source of Supply of compounded rubberdispersion such as rubber latex and such flexible hose for the spray gunI6 being indicated at 3i and connected to a source of supply of a liquidccagulant.

The cap 2t of each spray gun has a pair of lugs 32 projecting therefromat diametrically opposite sides of the air discharge opening 29 and eachlug 32 has a port 33 leading therethrough from the air chamber 25 to anoutlet 3d which discharges inwardly toward the combined compressed airand liquid discharge from the outlet 29 and nozzle 21 to flatten thespray discharge into a flat fan shaped spray 35.

The guns I5 and IG are arranged so that the lugs 32 of each are atopposite sides of a vertical plane so as to flatten the spray from eachgun into a fan shaped spray lying in a vertical plane and the combineddispersion and coagulant spray beyond the juncture of the sprays fromthe two guns is likewise a fiat fan shaped spray in a vertical plane andsprays only a narrow width of the belt Il] but throughout a substantiallength thereof, for example approximately 18 inches, substantially asindicated by the dotted lines at 30 in Fig. 1.

By moving the spray guns I5 and I6 back and forth along the track 22 atproper speed the spray 35 is caused to cover the entire width of thebelt Iii or such portion of the width as it is desired to cover with thespray.

Beyond the spray guns I5 and I6 toward the discharge end of the belt Iis another spray gun 31 directed straight down toward the belt I0 andsuspended from a carriage 38 which operates along an overhead track 39which, like the track 22 extends from side to side of the belt l0, saidgun 31 being located about fty inches from the guns I and I6 and aboutthirty inches above the belt I0.

This gun 31 is like the guns I5 and I6 in construction and has the ears32 thereof (see Fig. 3) arranged to hatten the spray 40 therefrom into aflat fan shape in a vertical plane extending lengthwise of the belt andaccordingly sprays only a narrow Width of the belt IIJ, but throughout aconsiderable length thereof, for example approximately ten totwenty-four inches, as indicated at 4I in Fig. 1.

Like the guns I5 and I6, this gun 31 is moved back and forth across thebelt Iii to cover the Width thereof, and this back and forth movement tothis gun, and to the guns l5 and I6 may be imparted manually or bypower.

The gun 31 sprays the dispersion only, without coagulant, and like thegun i5 has a iiexible hose connected thereto and leading from a sourceof compounded rubber dispersion which is discharged through the gunnozzle and another flexible hose connected thereto and leading from asource of compressed air to supply air under pressure for dischargethrough the cap of the gun around the tip of the nozzle in the samemanner as in the nozzles I5 and I6 of Fig. 3.

In order to avoid wastage of the sprayed material due to overspraybeyond the margins of the conveyor belt l0, and also to insureuniformity of spray application across the width of the conveyor belt,we provide a pair of corresponding long electrodes d2 which extend alongthe respective lateral margins of the belt l2 throughout the length ofthe spray zone as shown in 1 and 2. Each electrode 42 comprises anelongated wire frame of electrically conductive wire, substantially asdescribed in the co-pending sole application of Lucian P. Dosmann,Serial No. 41,528 (now Patent 2,595,342) filed January 30, 1948, andsaid frames are connected by spaced cross Wires d3, the number andlocation of which regulates longitudinal drift of spray mist. Theseelectrodes d2 are connected as indicated at ld to the negative pole of ahigh potential direct current generator t5, the other positive pole ofwhich. is grounded as indicated at i6 and as the underlying plate i3 isalso grounded at it as above mentioned, a positive charge iscommunicable to the plate I3 from the generator.

Thus, when the generator l5 is in operation a negative eld is createdand maintained over the belt between the electrodes and a correspondingpositive charge is accumulated in the plate. rlhis negative fieldcontributes a negative charge to the spray particles so that thenegatively charged electrodes d?. impose a barrier effect thereon toconfine and deposit the spray particles within the width of the belt I0,and thus avoid overspray and wastage, and it also causes the negativelycharged spray particles to be attracted to the belt by the positivelycharged plate I3 thereunder. The positive charge of the plate impa orcauses a positive polarity to exist in the upper surface of the belt itor the upper surface of any layers or deposit on the belt which polarityapparently tends to localize in any elevated or raised places on thesurface ci the belt, or or' any layers or deposit thereon and presentsgreatest attraction for the negatively charged partices at theseelevated or raised places.

For an appropriate and typical spraying operation with the aboveequipment, the gun I5 is provided with a nozzle 21 having a dischargeopening of 0.70 inch diameter and area of 2.47 sq. mm. and thedispersion is supplied to this nozzle through the hose 32 under apressure of 10 lbs. per square inch. The opening 29 around the nozzletip is of a rated capacity of 10.4 cubic feet of air at 50 lbs. pressureand the pressure ci the air supply 'through the hose 28 is 35 pounds persquare inch. Under these conditions the spray gun I5 will spray from 900to 1000 oc.

.75 dispersion per minute.

Thecoagulant 'gun I6 is providedwith a nozzle having a discharge openingof .052-inolfrdiarn.n eter and area of 1.37 sqmrn. and ,thel coagulantis suppiicd to this nozzle through the hose Si under a pressure of 3pounds per square inch. The opening 23 around the `nozzlefZI of thecoagulant gun I6 is of a rated capacity of v15.1 cubic feet of air at 50lbs. pressure vand the presn sure of air supply through the hose 28 ofthe gun i6 is the same as that supplied through the hose 25 of thedispersion gun I5, namely 35 lbs. per sq. inch. Underv these conditionsthe spray gun l will spray approximately 300 cc. Aof coagulant perminute.

The vertical gun 3l is provided with a nozzle il having a dischargeopening of .086 inch and area of 3.75 sq. mm. and the dispersion issupplied to this nozzle under a pressure of to l5 lbs. The opening 29around the nozzle 2l' of said gun is of a rated capacity of 15.1 cubicfeet of air at 50 pounds pressure and the pressure of supply to thechamber of said gun S'I and the opening le thereof is 60 pounds persquare inch. Under these conditions, the spray gun 3l will sprayapproximately 1200 cc. of dispersion per minute at l0 lbs. dispersionpressure, whereas at l5 lbs. ispersion pressure the deposit is abouti500 cc. per minute.

rubber dispersion such as disclosed in our application Serial No.550,964 may be employed for both guns I5 and 3l, but we prefer with theelectrode spray Icontrol to employ a compound less conducive to build upon the electrodes.

Such preferred dispersion is composed of the following:

Dry Weight Malayan latex 100.0 Potassium oleate Potassium oleate 0.5

En preparing this dispersion, the 0.5 part by weight of potassium oleateis added to the latex and stirred. The formaldehyde, potassiumhydroxide, and 0.3 part by weig t of potassium oleate are then added tothe latex mixture. Thereafter, the balance of the materials are added inthe order in which they are shown.

The castor oil soapy referred to in the above formula is composed of thefollowing:

Net Weight Castor oil 29.7 40% potassium hydroxide 13.25 Water 58.05

rEhe castor oil isheated to 2l0-220 F. and the 40% potassium hydroxideis added slovvly, thereto. The Water is then added and the mixture isstirred until free of lumps.

Any suitable coagulant may be employed inthe gun i6, such as aceticl orformic acid. We prefer to use acetic acid having a -20 per centconcentrationand this is .supplied to the `gun .I6 at a pressure of 3lbs. as aforesaid.

The spray fromthe `guns I5, Iand 3lmay be deposited .directly on thebelt .I0 to produce a layer of` material composed entirelyof the sprayparticles, and .which .is subsequently stripped fromV the belt or it`may be deposited as a surfacing on either a sheet materialsuch asindicated bydotted lines at I1-in Fig. 1 which is supported on andconveyed by the belt I0 continuously through the spraying, or` on.separate pieces of sections of sheety material whichare laid on theconveyer belt for conveyance, through the sprayingrzone.

Ifthe spray is deposited directly on: the belt and subsequently strippedtherefrom, We have found it desirable to lubricate the surface of thebelt with a soap solution prior .to the deposit of the spray thereon tofacilitate .thestripping of the completed layer fromI` the belt. Adesign, such as ribs, projections or indentationsmay be imparted to theunderside of the layer deposited thereon by engraving or embossing thereverse of such design on the belt I0, in which event it is especiallyimportant to apply the soap solution to the belt surface before sprayingthereon..v

When the dispersion is to be sprayed as a surfacing on a backing `orbase, such ,as the sheet material Il? of Fig. 2, or on separate piecesof backing material, such as sheets or pieces of rubber, fabric,cardboard, fibrous composition or the like, it is preferable to-prcoatthe.surfac e.there' of, on which the spray is'to be deposited, with anadhesive, such as a rubber cement, to insure .positive and permanentbonding of the sprayed surfacing thereto. 1 K I The surface ofthecmaterialxupon `which the spray is deposited may be embossedorotherwise provided with slight projectionsor. elevations, as shown moreparticularly inou' aforesaid application Seria-l No. 550,964, to`predetermine the places where the sprayed deposit builds up in theindividualized piles, althoughsuch embossments are not necessary with aspraying set up such as explained above, as` the` spray .fromY the gunI5 deposits a suicientscattering of relatively large droplets toinitiate pile-up in localized places and produce a random arrangement ofvclosely ad joining individualized piles.' Y v Y v With the gun openingsand. .pressures above indicated for the guns, the sprayed dispersionparticles appear tovbe generally of a yery-small size ranging indiametenfrom yabout 00015 to about .009302 but it appears 4thatiriidieltravel of the particles from the spray gun'tothe place of deposity someof these particles. accumulate into larger masses, this being due to andinfproportion to the volume of the spray lvhich-produces such profusionof spray particles that some of them crowd togetherand combine intolarger droplets'before deposit.

In any event, with the equipment above described, larger dropletsvareprducedu/hich providedeposits of approximate diameterfrom .020 to .035,and those fromthe spray gun. I5 are initially scattered indiscriminatelyon thedeposit surface in sunicent quantity .to initiate the build up .ofsubsequent deposits in close adjoining random arranged individualizedpiles. Subsequently deposited layer droplets accumulate generally in thethus initiated piles, those which are coagulated or largely coagulatedcontributing to depth of .build up and those Iwhich-area uncoagulatedseem to fill in between and around and knit the icoagulated. particlestogether-into a stable relatively solid mass and all of such subsequentlarge droplets tending by their size and impact to compact andcontribute density to the individualized piles.

1n this spraying operation, as the spray deposit is initiated, bothcoagulated and uncoagulated particles are deposited in fine particle andlarge droplets, the large drop-lets being scattered upon the surface, asindicated at 48 in Fig. 6, among a profusion of iine particles and, asthe spraying proceeds, the additional scattering of larger dropletsincreases the proximity of larger droplets to one another, and theparticles and droplets begin to pile up in the individualized piles,generally in the locations determined by the initial larger dropletdeposits 48, until close adjoining individualized piles are startedthroughout the sprayed surface, the proportion of uncoagulated particlesdeposited from the combined spray guns l and l5 being such as to knittogether the coagulated `particles and promote build up thereof tosubstantial height in individualized piles as the spraying proceeds.

In this initial build up of the individualized piles it is important tohave a proper ratio of coagulated and uncoagulated particles, inasmuchas lack of a suihcient proportion of uncoagulated particles results inan unstable mass and uncertain pile up, whereas an excess proportion ofuncoagulated latex prevents piling up of the coagulated particles orfloods out any formations which tend to accumulate or pile up.

W ith the above described set up, a suitable ratio of coagulated anduncoagulated particles is deposited by the guns I5 and I6 so that theparticles pile up readily in individualized piles somewhat as shown at49 in Fig. 8 and in random close adjoining distributed relation asindicated atr49 in Fig. '2, with a slight interconnection at the base asindicated at 50, these piles 49 being substantial in character butsupercially somewhat shaggy and of a loose texture capable ofaccommodating substantial additional quantities of uncoagulateddispersion.

Thereafter, as the deposit advances with the conveyor belt I@ theseindividual piles @is formed by the coagulant and dispersion mixture fromthe guns l5 and I6 come within the zone of the dispersion spray from thevertical gun 31, which as above explained deposits dispersion sprayonly, this spray of uncoagulated particles fills in further between andaround the particles of the piles d@ and on the surface thereof so thatthose piles di! become tough and durable lumps of relatively solidtexture, as indicated at 5l in Fig. 8, with the previous shaggy exteriormore or less filled in to produce a surface on each pile or lump whichis still rough and irregular but characterized by small blob-like lumps.

This dispersion spray from the gun 31 also lls in around and between theparticles of the interconnecting deposit SB at the bases 0f the piles togive greater solidity and depth thereto as indicated at 52 in Fig. 8.

Generally the deposit from the vertical gun 3l does not materiallyincrease the buildup of the piles d!! but is absorbed within and on thesurface or" the piles i9 to increase the solidity and strength thereof.

As above mentioned, an increasingly greater amount of uncoagulateddispersion can be accominodated as the piles 4S are built up and the setup shown in Figs. 1 and 2' is advantageous as it permits adjustment ofthe final application of uncoagulated particles to the particular volumethat can be accommodated by or is desired for the texture and surfacingof the piles. Moreover, build up between the piles depends largely uponthe relative volume of uncoagulated particles deposited and by adjustingthe volume of the spray from the gun 3l a deposit of greater or lesserdepth at 52 between the piles may be obtained.

In the above described spraying operation, the ratio of coagulant todispersion is about 1 to 9 and with the gun arrangement and spraydistance recommended above the ratio of coagulated to uncoagulatedparticles as they are deposited appears to be about 1 to 5.

Obviously the ratio of coagulated to uncoagulated particles depends uponthe particular dispersion compound employed, the strength and relativequantity of the coagulant, the size of the spray particles, thedistance, direction and force of the spray and the manner of exposure ofthe dispersion to the coagulant. For example, by atomizing thedispersion to an extremely line spray we have employed a front gundispersion discharge of 600D cc. per minute with the 300 cc. per minuteof coagulant.

Generally, individualized formations may be produced with a ratio ofcoagulant to dispersion as low as l to l. and as high as 1 to 25 andwith a ratio of coagulated particles to uncoagulated particles as low asl to 2 and as high as 1 to 6. The particles which produce the build upmay not be completely coagulated but are suiciently coagulated so theyare suiiiciently set to accumulate in piles and do not accumulate asliquid.

With the above described set up, the nozzles l5, l5 and 37 are movedback and forth across the top of the conveyor during the sprayingoperation so as to distribute the deposit evenly across the width of thebelt, and when thus operatedacross the five foot Width of the belt I l!at the above indicated preferred belt spread they deposit about cc. ofdispersion per square foot, which produces a deposit of approximately1/8 inch over all depth which is generally sufficient for many purposes,especially coatings for trimstock for automobiles and the like. For suchsingle pass operation we generally use a dispersion pressure of about l0lbs, at the nozzle 3l and the volume of dispersion supplied therefor isabout 2200 cc. per minute.

For thicker stocks, such as carpeting or automobile mats, the volume ofthe spray may be increased but we have found it advantageous to eifectsuch increase by two passes through the spraying zone. Because a greatervolume of dispersion may be accommodated as the piles build up, weprefer on the second pass to increase the dispersion pressure of thenozzle 31 to 15 lbs. which increases the volume of dispersion dischargeto about 2809 cc. per minute.

Thus the material represented in Fig. 8, which is produced in a singlepass through the spraying zone on the conveyor lil, is passed againtherethrough and thereby the formations 5l on the f Fig, 8 material arebuilt up to an increased height substantially as shown in Fig. 9.

In this second pass the mixed coagulated and uncoagulated particles fromthe gun l5 pile up on top of the already produced piles 5l in somewhatscraggly loose textured accumulations as represented at 53 in Fig. 9with some increase in the interconnections between the piles, asindicated at 5d after which the dispersion from the gun 31 fills in onand between the particles of the additionally piled up masses 53 and inand on the 11 particles of the additional interconnecting deposit 54 andimparts a solidity of texture and surfacing to the added deposit likethat f the original piles l In this second pass the deposit accumulatesto an overall depth of approximately one quarter of an inch and thematerial resembles andmay be used like a pile carpeting.

The material of Fig. 8 or the two pass material of Fig, 9 may bedeposited ony the belt surface and stripped therefrom, or maybedeposited on a backing, which is indicated by dotted lines at 5l inFigs. Sand 9, the backing being preferably coated with a cement asindicated at vbefore the deposit is applied therein.

The deposited dispersion is compounded with Vul'canizing ingredients andafter the spraying operation is completed it is vulcanized.

An alternative form of spraying equipment is represented in Figs. 4 and5 in which three fixed guns 59, G and Si are located in superpcsedrelation above the belt I@ midway between the length thereof. Thesegunsare similar tothe guns l5, i6 and 3l, the upper and lowerguns beingsupplied with the dispersion compound and air under pressure tospray'dispersion only, and the middle gun @d being supplied withcoagulant and compressed air to spray ccagulant only.

All of these guns 5s, 6Fl and 6l are provided with spray flatteningfacilities, like the lugs 32 and ports 33 and outlets 3ft of thepreviously described guns, but arranged above and below the spraydischarge to ila-tten the spray into fan shapev spreading widthwise ofthe belt, the guns 59, G0 and Sl being arranged so as to converge andmet at a distance therefrom, as indicated in Fig. and produce acomposite spray which fans out across the belt'to substantially the samewidth as the belt at the-place where the spray deposits thereon.

In this set up, the upper dispersiongun 5I is located at an elevation ofabout 2l inches above the belt and tipped down at an angle of about 30,or in some cases as much as 60, to the plane of the belt, and thecoagulant gun'ii is located about 13 or 14 inches above the belt andtipped down at an angle of about 15 to the plane of the belt while thelower dispersion gun is located cout 9 inches above the belt and tippedup slightly, about 5, to the plane of the belt.

Substantially the same total deposit of dispersion is employed intheabove described set up of Figs. I and 5 as in the set up of Figs. 1and 2 and substantially the same ratio of coagulant to total dispersionis employed7 this total-dispersion being proportioned between the upperand lower guns 6l and 59 to accomplish the same char acter of build upand solidication of the individualized piles as produced by the set upof Figs. l and 2.

Generally the dispersion from the upper gun 6l supplies the uncoagulatedparticles which accomplish the eventual lling in and solidification ofthe piles which is eifectedlargely by the vertical gun 3l of the Figs.land 2 set up and supplies a greater volume of dispersion than the lowergun 59.

Preferably electrostatic control, corresponding to the electrodes 42 andcross wires 43 of Figs. 1 and 2, is employed in conjunction with the setup of Figs. 4 and 5 to avoid overspray at the margins of the belt and tofacilitate localized deposit.

This set up of Figs. 4 and 5 provides a width of spray which extendsacross and covers the width of the belt without the `necessity of movingthe Cir -12 spray guns vbaclrfand forth across the belt, but does notgive as great uniformity of spray throughout the width of the belt asmay be obtained with the movable guns of Figs, l and 2. For surfacingpieces of backing material, such non-uniformity is not objectionable.

In spraying with either set up on pieces of backing materials, selectedportions only of the surfaces of lthe pieces may be surfaced by overlapping .the pieces so that portions of the surfaces are masked out.

In the spraying operations above described, the dispersion' deposits' inpronounced more or less finger-like piles or lumps, which however aresufficiently interconnected 'with one another throughout the area of thematerial to consftute a continuity of piles or lumps.

It is to be understood that while we have specilied av particular latexcompound that may be used in the spraying operation, our inventioncontemplates not only natural latex but also dispersions- 0f syntheticrubber or of any other similar elastic materials that may be employedfor the' purpose, all of which are contemplated in the term rubberasused`in' the claims hereof.

While we have shown and described our invention in a preferrediform, weare aware that various changes and modications may,7 be made thereinwithout departing from the spirit of our invention, the scope of whichis to be determined by the appended claims.

What is claimed:

l. The method ofV making a lumpy layer of elastic material withpronounced lumpmlike formations substantially individualized andproximately` arranged throughout the area thereof, which-said methodcomprises providing a surface, on vwhich the layer is to be made, withinitial elevationsat the respective places where the lump-likeformationsare to be produced thereon and thereafterv depositing on saidsurface a relatively smallquantity-of stable particles of a coagulableliquid dispersion'of rubber together with a substantially largerquantityof unstal'le particles thereof,=the amountof which unstableparticles is suflicient-for complete coverage of said surface toa'substantial depth,'and includes the steps-of spraying the coagulableliquid dispersion of rubber -in finely -dividedl particles to providethe particles' which aredeposited on said surface as aforesaid,depositing-those sprayed particles which compose the aforesaidsubstantially larger quantity on-said surface before coagulationthercof, separately sprayingI andA commingling with the spray of'coagulable lliquid dispersion particles'while the latter are inI transitto said surface, finely divided particles of a coagulant whichcoagulates those sprayed particles which compose the aforesaid smallquantity'of stable particles before depositv thereof on said surface,piling up the coagulated particles locallyon the respective aforesaidinitial elevations of said surface in superposed relation to one anotherin pronounced substantially individualized piles, and as said coagulatedparticles'areaccumulatingin said piles, progressively accumulatingtherewith and retainn ing locallyon and in'said piles the saiduncoagulated particles.

2. The method of making a lumpy layer of elastic material withpronounced substantially solid lump-likelformations substantiallyindividualized and proximately arrangedthroughout the area thereof,which said method-comprises providing a surface, on which the' layer isto be made, with initial elevationsatltherespective places where thelump-like formations are to be produced thereon and thereafterdepositing on said surface a relatively small quantity of stableparticles of a coagulable liquid dispersion of rubber together with asubstantially larger quantity of unstable particles thereof, the amountof which unstable particles is suiiicient for complete coverage of saidsurface to a substantial depth and includes the steps of spraying thecoagulable dispersion of rubber in nely divided particles to provide theparticles which are deposited on said surface as aforesaid, depositingthose sprayed particles which compose the aforesaid substantially largerquantity on said surface before coagulation thereof, separately sprayingand commingling with the spray of coagulable liquid dispersion particleswhile the latter are in transit to said surface, iinely dividedparticles of a coagulant which coagulates those sprayed particles whichcompose the aforesaid small quantity of stable particles before depositthereof on said surface, piling up the coagulated particles locally onthe respective aforesaid initial elevations of said surface insuperposed relation to one another in pronounced substantiallyindividualized piles, and as said coagulated particles are accumulatingin said piles, progressively accumulating therewith and retaininglocally on and in said piles the said uncoagulated particles andprogressively combining said uncoagulated particles with the coagulatedparticles in a relatively solid lump-like mass.

3. The method of making a lumpy layer of elastic material withpronounced substantially solid lump-like formations substantiallyindividualized and proximately arranged throughout the area thereof,which said method comprises providing a surface, on which the layer isto be made, with initial elevations at the respective places where thelump-like formations are to be produced thereon and thereafterdepositing on said surface a relatively small quantity of stableparticles of a coagulable liquid dispersion of rubber together with asubstantially larger quantity of unstable particles thereof, the amountof which unstable particles is suicient for complete coverage of saidsurface to a substantial depth and includes the steps of spraying thecoagulable liquid dispersion of rubber in finely divided particles toprovide the particles which are deposited on said surface as aforesaid,depositing those sprayed particles which compose the aforesaidsubstantially larger quantity on said surface before coagulationthereof, separately spraying and commingling with the spray ofcoagulable liquid dispersion particles while the latter are in transitto said surface, finely divided particles of a coagulant whichcoagulates those sprayed particles which compose the aforesaid smallquantity of stable particles before deposit thereof on said surface,piling up the coagulated particles locally on the respective aforesaidinitial elevations of said surface in superposed relation to one anotherin pronounced substantially individualized piles, and as said coagulatedparticles are accumulating in said piles, progressively accumulatingtherewith 6 and retaining locally on and in said piles the saidunccagulated particles and progressively combining said uneoagulatedparticles with the coagulated particles, and finally depositing on saidpiles and accumulating thereon in integral relation therewithuncoagulated particles of another separately sprayed coagulable liquiddispersion of rubber.

4. The method of making a lumpy layer of elastic material withpronounced substantially solid lump-like formations substantiallyindividualized and proximately arranged throughout the area thereof,which said method comprises providing a surface, on which the layer isto be made, with initial elevations at the respective places where thelump-like formations are to be produced thereon and thereafterdepositing on said surface a relatively small quantity of stableparticles of a coagulable liquid dispersion of rubber together with asubstantially larger quantity of unstable particles thereof, the amountof which unstable particles is suiiicient for complete coverage of saidsurface to a substantial depth, and includes the steps of spraying thecoagulable liquid dispersion of rubber in iinely divided particlesthrough an electrical field of given polarity to provide andelectrically charge the particles which are deposited on said surface asaforesaid, imparting an electrical charge of opposite polarity to saidsurface, depositing those sprayed particles which compose the aforesaidsubstantially larger quantity on said surface before coagulationthereof, separately spraying and commingling with the spray ofcoagulable liquid dispersion particles while the latter are in transitto said surface, finely divided particles of a coagulant whichcoagulates those sprayed particles which compose the aforesaid smallquantity of stable particles before deposit thereof on said surface,piling up the coagulated particles locally on the respective aforesaidinitial elevations of said surface in superposed relation to one anotherin pronounced substantially individualized piles, and as said coagulatedparticles are accumulating in said piles, progressively accumulatingtherewith and retainl ing locally on and in said piles the said uncoag-References Cited in the le of this patent UNITED STATES PATENTS NumberName Date 2,056,406 Mayne Oct. 6, 1936 2,120,406 Hansen June 14, 19382,155,441 Osborne Apr. 25, 1939 2,184,153 Schwartz Dec. 19, 19392,249,205 Hansen July 15, 1941 2,335,116 Hansen Nov. 23, 1943 2,421,787Helmuth June 10, 1947 2,501,839 Bodle et al Mar. 28, 1950 2,502,445 FashApr. 4, 1950 2,595,342 Dossmann May 6, 1952 FOREIGN PATENTS NumberCountry Date 795,338 Great Britain Mar. 11, 1936

1. THE METHOD OF MAKING A LUMPY LAYER OF ELASTIC MATERIAL WITHPRONOUNCED LUMP-LIKE FORMATIONS SUBSTANTIALLY INDIVIDUALIZED ANDPROXIMATELY ARRANGED THROUGHOUT THE AREA THEREOF, WHICH SAID METHODCOMPRISES PROVIDING A SURFACE, ON WHICH THE LAYER IS TO BE MADE, WITHINITIAL ELEVATIONS AT THE RESPECTIVE PLACES WHERE THE LUMP-LIKEFORMATIONS ARE TO BE PRODUCED THEREON AND THEREAFTER DEPOSITING ON SAIDSURFACE A RELATIVELY SMALL QUANTITY OF STABLE PARTICLES OF A COAGULABLELIQUID DISPERSION OF RUBBER TOGETHER WITH A SUBSTANTIALLY LARGERQUANTITY OF UNSTABLE PARTICLES THEREOF, THE AMOUNT OF WHICH UNSTABLEPARTICLES IS SUFFICIENT FOR COMPLETE COVERAGE OF SAID SURFACE TO ASUBSTANTIAL DEPTH, AND INCLUDES THE STEPS OF SPRAYING THE COAGULABLELIQUID DISPERSION OF RUBBER IN FINELY DIVIDED PARTICLES TO PROVIDE THEPARTICLES WHICH ARE DEPOSITED ON SAID SURFACE AS AFORESAID, DEPOSITINGTHOSE SPRAYED PARTICLES WHICH COMPOSE THE AFORESAID SUBSTANTIALLY LARGERQUANTITY ON SAID SURFACE BEFORE COAGULATION THEREOF, SEPARATELY SPRAYINGAND COMMINGLING WITH THE SPRAY OF COAGULABLE LIQUID DISPERSION PARTICLESWHILE THE LATTER ARE IN TRANSIT TO SAID SURFACE, FINELY DIVIDEDPARTICLES OF A COAGULANT WHICH COAGULATES THOSE SPRAYED PARTICLES WHICHCOMPOSE THE AFORESAID SMALL QUANTITY OF STABLE PARTICLES BEFORE DEPOSITTHEREOF ON SAID SURFACE, PILING UP THE COAGULATED PARTICLES LOCALLY ONTHE RESPECTIVE AFORESAID INITIAL ELEVATIONS OF SAID SURFACE INSUPERPOSED RELATION TO ONE ANOTHER IN PRONOUNCED SUBSTANTIALLYINDIVIDUALIZED PILES, AND AS SAID COAGULATED PARTICLES ARE ACCUMULATINGIN SAID PILES, PROGRESSIVELY ACCUMULATING THEREWITH AND RETAININGLOCALLY ON AND IN SAID PILES THE SAID UNCOAGULATED PARTICLES.